49PCS Thread Repair Chaser Kit UNC /NF Metric Thread Restorer Tap and Die Tool
The thread chaser kit and each holes of the box are marked the specification, which can help you to find the right one you need quickly. National Fine(NF) Sizes: 1/4"-28, 5/16"-24, 3/8"-24, 7/16"-20, 1/2"-20, 9/16"-18, 5/8"-18.